Heretofore, when a lens such as a spectacle lens is processed so that the lens is fitted into the lens portion of a spectacle frame, the peripheral face of an uncut lens is ground by a grinder or cut by a cutter, and the uncut lens is formed into a prescribed shape of the peripheral portion in accordance with data of the shape of the lens portion of the spectacle frame.
Examples of a known processing apparatus for this purpose include, as disclosed in Japanese Patent Application Laid-Open No. 2002-18686, apparatuses in which a rotating tool (a grinder), which can be freely rotated and grinds the peripheral face of the lens, is disposed around a first shaft on a base. The position of grinding or cutting is set by driving a second shaft supporting the lens, which can be freely swung relative to the first shaft of the rotating tool, towards the first shaft of the rotating tool by an arm, and rotating the lens around the axis of the second shaft.
These apparatuses are equipped with a control portion in which selections are made among the types of processing such as the flat processing and the beveled processing and selection among the modes of processing are made such as the crude processing, finishing, mirror finishing, grooving and chamfering. The pressure of chucks and the tools used for the processing are set in accordance with the material of the lens (glasses, plastics, polycarbonates and acrylic resins). The peripheral portion of the lens is processed based on shape data of the lens frame.
In recent years, various types of resins are used for the lens so that the refractive index is increased and the impact resistance is improved. Processability is different depending on the material.
In the conventional apparatuses described above, processing is conducted by setting the processing condition such as the direction of rotation of the lens axis (the up cut and the down cut) and the presence or the absence of water supply in accordance with the material of the lens. When a lens made of a new material is processed, occasionally, the conditions which can be set are insufficient, and processing cannot be conducted smoothly.
For example, as disclosed in Japanese Patent Application Laid-Open Nos. 2000-511231 and 2002-504935 (PCT National Phase Applications), the processing of a lens exhibiting excellent impact resistance such a lens made of a polyurethane-based resin, which is formed with a polyurethane material prepared from an aliphatic diisocyanate compound, an intermediate compound having hydroxyl group selected from polyester glycols, polyether glycols and mixtures of these glycols and a curing agent of an aromatic primary diamine, has certain problems. For example, melted dust and debris of grinding having the shape of ribbons and strings is occasionally attached at the peripheral portion of the processed lens in both of wet processing using cooling water and dry processing without using cooling water, and the dust and debris at the peripheral portion of the lens must be manually removed after the processing has been conducted. This procedure increases the time and the labor required for the processing of the lens.